The present invention relates generally to a data storage tape drive system. More particularly, it relates to an engagement control feature of a drive chuck component of a tape drive mechanism that improves operative engagement between the data storage tape cartridge and the tape drive mechanism.
Data storage tape drive systems are commonly used in the computer, audio, and video fields to record and store large volumes of information for subsequent retrieval and use. A data storage tape drive system generally includes a data storage tape cartridge selectively engaged with a tape drive mechanism. In this regard, the data storage tape cartridge generally consists of an outer shell or housing maintaining at least one tape reel and a length of magnetic storage tape. The tape reel is rotatably disposed within the housing, and a length of the storage tape is wound about a hub portion thereof The tape drive mechanism generally includes a drive chuck configured to operatively engage and rotate the tape reel, and a drive motor for controlling the drive chuck. The tape drive mechanism also includes transducers, such as a magnetic read/write head, for interacting with and recording data to, or reading data from, the storage tape.
Operative engagement between the data storage tape cartridge and the tape drive mechanism includes engagement of teeth formed on the drive chuck with teeth formed on the tape reel. When mated, these teeth act both to locate the tape reel relative to the drive chuck, and to transmit torque from the tape drive motor/chuck to the tape reel. To this end, one typical tooth design entails sixty teeth on both the tape reel and the drive chuck. As used throughout the specification, the tape reel teeth situated to interact with the tape drive are referred to as xe2x80x9ctape reel teethxe2x80x9d or xe2x80x9creel teethxe2x80x9d, whereas the corresponding tape drive/chuck teeth are referred to as xe2x80x9cdrive chuck teethxe2x80x9d or xe2x80x9cdrive teethxe2x80x9d.
Regardless of the number of teeth, upon insertion of the tape cartridge into the drive, the tape reel is generally aligned with the drive chuck. The drive chuck is then maneuvered toward the tape reel (and/or the tape reel is maneuvered toward the drive chuck) such that the drive chuck teeth are guided into mesh engagement with the reel teeth. This meshed relationship facilitates rotation of the tape reel by the drive chuck. At any one point in time, however, only three of the tape reel teeth are in true contact with the drive chuck teeth, as plane of interface can only be defined by three points. Unfortunately, it is virtually impossible with current tape reel designs to predict or dictate which three reel teeth will define the interface plane. As a point of reference, the tape reel components, including the reel teeth, are plastic molded parts. Molding imperfections in the surface of the tape reel teeth, systematic deviations in angular spacing of the teeth due to an off-centered gate location and/or cooling profile, trapped debris, and/or tooth damage due to wear all contribute to defining which three teeth on the tape reel actually contact/engage the drive chuck teeth. Formation of the drive chuck teeth may give rise to similar concerns. Pitch and gear tooth geometry variability due to molding both result in a non-consistent datum reference in the tape reel and drive chuck. This often results in excessive radial and axial run-out that adversely affects reading/recording operations of the tape cartridge. In effect, molding/fabrication imperfections can result in the tape reel rocking or wobbling on the drive chuck during use.
Previously, for several types of tape drive systems, skewing and/or misalignment between the tape reel and the drive chuck did not adversely affect ultimate positioning of the storage tape relative to the read/write head. With a 3480-type (or single reel) tape cartridge, for example, the storage tape is directed a relatively long distance from the housing to the read/write head. Thus, interaction between the read/write head and the storage tape takes place away from the housing and, therefore, away from the tape reel. The relatively ample tape length between the housing and the transducers compensates for skewing and/or misalignment between the tape reel and the drive chuck during operative engagement. Unfortunately, new data storage tape drive systems no longer afford such generous spacing between the housing of a single reel data storage tape cartridge and the transducers of the tape drive mechanism. Further, the continued evolution of storage tape technology toward increasingly smaller track widths amplifies the potential for radial and/or axial misalignment-caused errors. While efforts can be made to more precisely mold/fabricate the tape reel and/or drive chuck teeth, the large increase in cost renders such design efforts economically unviable. Further, some efforts have been made to improve axial alignment or datum plane interaction via additional alignment feature(s) formed on the tape reel as described, for example, in U.S. Pat. No. 6,273,352 to Johnson et al. While most certainly minimizing the opportunity for axial runout, the Johnson et al. configuration does not appear to fully address radial run-out. That is to say, Johnson et al. continues to rely upon the pitch/meshing of the reel teeth and drive chuck teeth to radially locate the tape reel relative to the drive chuck. As previously described, this approach, while well-accepted, cannot eliminate radial run-out concerns.
Accordingly, a need exists for a data storage tape drive system that accurately and consistently controls and aligns, both radially and axially, operative engagement between a tape reel of a data storage tape cartridge and a drive chuck of a tape drive mechanism.
One aspect of the present invention relates to a drive chuck of a tape drive mechanism for operatively engaging a tape reel of a data storage tape cartridge. In this regard, the tape reel includes a circular ring of outwardly projecting reel teeth that defines inner and outer circumferential faces. With this in mind, the drive chuck includes a circular ring of drive chuck teeth and an alignment feature. The alignment feature is radially spaced from the drive chuck teeth and includes a radial contact surface. In this regard, the radial contact surface is configured and positioned to contact one of the inner and outer circumferential faces upon engagement between the drive chuck and the tape reel. In one preferred embodiment, the alignment feature is a ring positioned to contact the outer circumferential face of the ring of reel teeth.
Another aspect of the present invention relates to a data storage tape drive system including a data storage tape cartridge and a tape drive mechanism. The data storage tape cartridge includes a housing, a tape reel, and a storage tape. The housing defines a tape reel opening. The tape reel is rotatably disposed within the housing at the tape reel opening and includes a circular ring of outwardly projecting reel teeth. In this regard, the ring of reel teeth defines an inner circumferential face and an outer circumferential face. The storage tape is maintained by the tape reel. The tape drive mechanism is adapted to selectively engage the data storage tape cartridge and includes a drive chuck. The drive chuck includes a circular ring of outwardly projecting drive chuck teeth and an alignment feature. The alignment feature is radially spaced from the drive chuck teeth and projects in a direction generally parallel to an axis of rotation. In this regard, the alignment feature is engaged with one of the inner and outer circumferential faces of the ring of reel teeth when the drive chuck is operatively engaged with the tape reel so as to radially align the tape reel relative to the drive chuck.
Yet another aspect of the present invention relates to a method of operatively engaging a drive chuck of a tape drive mechanism with a tape reel of a data storage tape cartridge. In this regard, the drive chuck includes a circular ring of outwardly projecting drive chuck teeth, whereas the tape reel assembly includes a circular ring of outwardly projecting reel teeth that defines an inner circumferential face and an outer circumferential face. The method includes operatively engaging the drive chuck teeth with the reel teeth and contacting one of the inner and outer circumferential faces of the circular ring of drive teeth with an alignment feature of the drive chuck. This contact radially aligns the tape reel relative to the drive chuck.